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Neuroradiology Case of the Week

Case 231

Chandler Shyu, MD and P-L Westesson, MD, PhD, DDS

Clinical Presentation: An 88-year-old female presented to the ED after a fall. Head CT was performed to evaluate for intracranial injuries.

Imaging Findings: Head CT was negative for acute trauma. However, there was incidental note of a well-circumscribed, smoothly marginated sclerotic mass arising from the wall of the frontal sinus.

Diagnosis: Frontal sinus osteoma

Discussion: Osteoma is a benign osteoblastic tumor usually found as an incidental finding in neuro imaging. They arise from membranous bone in the outer table of the skull or the frontal and ethmoid sinuses. Osteoma can also occur in tubular long bone (humerus/femur) and are called parosteal osteoma at these sites.  They are found equally in men and women, most commonly in the fourth to fifth decade of life.
     Typical radiographic appearance is a round or lobulated, sharply marginated sclerotic mass with average size of 2-3 cm.
      Osteomas are for the most part an asymptomatic lesion, however infrequently they can cause local pain or headaches due to sinus obstruction. Osteoma, especially if multiple, is also associated with Gardner syndrome. Gardner syndrome is a familial autosomal dominant disorder characterize by cutaneous/subcutaneous masses and more importantly, adenomatous colonic polyps with potential for malignant degeneration.

Key Points:

• Benign tumor commonly found in the calvarium and frontal/ethmoid sinuses as a well circumscribed sclerotic mass with smooth margins.
• Associated with Gardner syndrome.

References:

1. Price HI, Batnitzky S, Karlin CA, Gilmore RL. Computed tomography of benign disease of the paranasal sinuses. RadioGraphics 1983; Mar-Apr 3(1):107-140. [PDF]
2. Greenspan A . Orthopedic Radiology: A Practical Approach . 3rd Ed., Philadelphia: Lippincott Williams & Wilkins, 2000;547-550.